As the years go by, video game aliens have gotten uglier, meaner, and bigger. A perfect example of such games is Halo and Gears of War. Before you will be able to destroy such aliens, you should first soak them up with plenty of bullets.
The invaders in "XCOM: Enemy Unknown" are ruthless and they have come to Earth to destroy humanity. Sectoids are the first alien that you will encounter. Such aliens look like stiff breeze and they carry a laser gun that would disintegrate human flesh. As a matter of fact, some of them take over helpless Earthling minds. "XCOM" is the golden age of science fiction. It is just a typical story with a stalwart of men and women that would stand up against overwhelming odds.
There is also Thin Men and they are bioengineered so that they will look like real humans. There is also insectoid Chrysalids that lay eggs in their human victims. Once they lay their eggs in their human victims, the human will become zombies and once they explode they will become new monsters.
In this video game, there are deranged scientists who are obsessed in studying alien technology instead of having the concern of saving the planet. There is also a shadowy council that keeps on pushing you to fight without providing you the resources you actually need.
Once you are on the field, you will have four types of troopers. The first is the assault troop who is skillful when it comes to close combat. The second is the Heavy troop who can lug around machine guns as well as rocket launchers. The third is the support troop who creates good medics and the last troop is the snipers. Snipers can be very deadly at long distances. The troops can be very skillful once they survive more missions. You definitely need a good mix to increase your chance of winning.